The Cryopreservation and Rederivation programs of The Jackson Laboratory (TJL) serve TJL Cancer Center members by ensuring that all strains imported to TJL are free of potential infectious pathogens and that research strains are cryopreserved to ensure continued availability and to guard against accidental loss. Both of these programs utilize state-of-the art reproductive technology in a new facility designed for optimal integrated functionality and both programs are absolutely essential to our operation as a research laboratory focused on mammalian genetics. In this application funds are requested to support: 1) the importation of approximately 50 strains per year for individual TJL Cancer Center members, 2) the rederivation of strains within the Research Animal Facility as part of a program to operate the facility as a barrier facility with all animals at uniform health status; and 3) the cryopreservation of approximately 40 strains developed or acquired by TJL Cancer Center members per year.